1. Field of the Invention
The present invention relates to a service apparatus, a method of controlling switching of connection destination of a client apparatus by the service apparatus, and a storage medium readable by a machine.
2. Description of the Related Art
Since communication by a wireless LAN (Local Area Network) has no limitation on wiring and is high in convenience, various service apparatuses and service methods of the wireless LAN have been studied.
A system of the wireless LAN includes an access point of the wireless LAN (which may be hereinafter simply referred to as “access point”) and a communication apparatus of the wireless LAN that is connectable to the access point through radio transmission (which may be hereinafter simply referred to as “client”).
When a user uses the wireless LAN, the client sends a packet, which includes identification information called an SSID (Service Set ID) capable of identifying the access point and an MAC (Media Access Control) address serving as identification information of the client, as a connection request.
When the connection request reaches the access point, the access point reads the SSID and the MAC address from the packet of the connection request. The access point uses the SSID to judge whether the connection request is a request for connection to the own access point.
As a result of the judgment, if the connection request is not a request for connection to the own access point, the access point does not send a response to the MAC address that is received simultaneously with the SSID. On the other hand, as a result of the judgment, if it is judged that the connection request is a request for connection to the own access point, the access point sends a response to the MAC address that is received simultaneously with the SSID. In this way, the client and the access point are connected.
Next, a case in which there are plural access points will be explained. The respective access points have a common SSID. When a packet of a connection request is received from a client, if it is possible to respond to this connection request, the respective access points give MAC addresses of the own access points to packets for response and respond to the connection request.
When the client receives response packets from the plural access points, the client measures reception intensities of the respective packets and makes connection to the access point with the highest signal intensity through the MAC address.
Thereafter, the access point connected to the client notifies the other access points of that the access point is connected to the client by using a broadcast packet. In this way, when there are plural access points, an access point selected on a client side and the client are connected. Then communication of the wireless LAN is performed between the access point and the client.
The followings are related arts to the present invention.
When there are plural clients for one access point, throughput per one client falls as the number of clients increases. In this case, it is necessary to maintain throughput of the clients in a practical range.
In order to solve the problem, it is conceivable to decentralize access points to which clients establish connection by setting the number of access points to the equal to the number of clients. However, as described above, since the clients establish connection to an access point with a highest signal intensity, it is likely that accesses from plural clients concentrate on a specific access point. In this case, it is impossible to realize decentralization of proper accesses.
In addition, it is also conceivable to realize decentralization of access points by assigning a different SSID to each client and limiting access points that respective clients can use. However, in this case, since the number of access points that the clients can use decreases, it is likely that locations where wireless LAN communication can be performed satisfactorily are limited.
Moreover, the patent document 1 discloses a method of changing a radio channel of a client connected to an access point handling high traffic to a radio channel of another access point. However, in the method disclosed in the patent document 1, it is necessary to add new functions to firmware of access points and radio drivers of clients. Therefore, it is necessary to modify both the access points and the clients.
[Patent document 1] Japanese Patent Laid-Open Publication No. 2001-237856
[Patent document 2] Japanese Patent Laid-Open Publication No. 2002-185458
[Patent document 3] Japanese Patent Laid-Open Publication No. 2003-174456
[Patent document 4] Japanese Patent Laid-Open Publication No. 2004-140614
[Patent document 5] Japanese Patent Laid-Open Publication No. 2004-221684